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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>typeof学习</title>

    <script>
        var a = 'w';
        console.log(typeof(a)); //string
        var b = 23;
        console.log(typeof(b)); //number
        var c = true;
        console.log(typeof(c)); //boolean
        var d = null;
        console.log(typeof(d)); //object
        var e = undefined;
        console.log(typeof(e)); //undefined
    </script>

</head>

<body>

</body>

</html>